April is the start of ozone season in North Carolina, and is a reminder that there is actually too much ozone in our atmosphere – or at least in part of it.
Ozone, or O3, is a gas that resides in two layers of the atmosphere: the troposphere, the first 11 kilometers above the surface of the earth, and the stratosphere, which extends from 11 to 50 kilometers above the earth.
“There is a paradox associated wi t h t he presence of ozone in these two layers,” said Viney Aneja, professor of air quality and environmental technology. “Ozone gas is beneficial to humankind when it is in the stratosphere, but it is harmful to us when it is in the troposphere. The same molecule in one place is good for us but in another place is bad for us.”
According to Aneja, ozone has caused the most troublesome air pollution problem for our nation, as when it’s in the troposphere it leads to a variety of health problems. Ozone increases with car emissions and is a very powerful oxidant. Once it is breathed in it causes damage on the cellular level, causing lung damage and inhibiting a person’s ability to breath.
“Ozone is a very reactive chemical, and when it gets into the respiratory system it can cause a lot of damage, especially if people already have an existing respiratory condition,” Chris Frey, professor of environmental engineering, said.
In addition to causing or enhancing a variety of respiratory disorders, ozone also damages crops. According to Frey, ozone was responsible for billions of dollars’ worth of damages reported on crops nationwide.
Aneja said that ozone is formed in the troposphere by the reaction of gasses to sunlight. Oxides of nitrogen (NOX), a gas largely emitted by fossil fuel combustion, react with volatile organic compounds (VOCs) created by both fossil fuels and vegetation, creating tropospheric ozone.
April is the start to ozone season because ozone levels are influenced by the weather – if the temperature increases, ozone formation will also increase. Dramatic shifts in wind patterns also have noticeable effects on ozone levels. Ozone is a particular problem in the Charlotte metropolitan area and the Triad Region because of the large amount of traffic they attract.
However, the situation is improving. In recent years, ozone levels have been lower for the triangle area. One reason for this noticeable decrease is the improvement of the automotive fleet in terms of emissions, which has led to a decrease in NOX. The other contributing factor is the transition from old coal power plants to more efficient power plants across North Carolina.
This ozone season, residents can check the air quality index online. The air quality index will accurately reflect the levels of ozone and other pollutants in the air on any given day. When the air quality on a given day is less than ideal, there are certain steps that can be taken to avoid health risks.
When the air quality index is orange or higher, children and the elderly should remain inside. People should avoid physical activity in the middle of the day during days of dangerous air quality.
